Cyclical impulses in the analysis of macroeconomic fluctuations.

Summary A primary objective of this research is to identify the nature of the impulses behind the cyclical macroeconomic fluctuations observed in the main OECD countries. Beyond this identification, the aim is to demonstrate their impact on the level of economic activity and their degree of persistence. We therefore explicitly adopt the impulse-propagation approach for which economic fluctuations result from the propagation of exogenous shocks. This thesis brings original elements of evaluation to the debate on the sources of impulse of economic fluctuations that dominated the macroeconomy of the 1980s. The application of recent developments of the vector autoregressive methodology has led to enlightening results: domestic demand shocks contribute substantially to the variability of short-term activity. These shocks cause a positive and persistent response of the product. foreign demand shocks also have a stimulating effect on fluctuations. The convergence of these results for different countries reinforces their significance. We have sought to exploit them theoretically by studying the properties of an original model: the inclusion of government expenditure shocks in a two-country real business cycle model significantly improves its ability to reproduce the characteristics of observed international fluctuations, but is not sufficient to eliminate all the shortcomings of such a model. Our thesis therefore argues in favor of a syncretic view of economic fluctuations.